> On Jun 8, 2023, at 1:18 PM, Adrian Godwin <[email protected]> wrote:
>
> ...
> I've seen mylar tape used in a tiny loop where it controlled the movements of
> a printer platen. I don't recall now whether it was used for horizontal or
> vertical space - my recollection was the latter but it was a long time ago.
>
> I don't know why it wasn't controlled by ASCII - a good bit of the character
> set is dedicated to print head control. I think a different tape had to be
> installed to match the program that was being run. The machine was used for
> accountancy in about 1975, It was a bit like a large LA120 (but included the
> calculating part) and made by the french Logabax company.
Many line printers used a "VFD" tape (vertical format definition?) which is a
12-channel tape with one row per line on the paper. The idea was that you
could tell the printer "skip to channel N" and it would advance the paper until
a hole in that channel was seen. By convention, channel 1 marks the top of the
page, and in fact typically that position was punched all the way across so a
skip to an "unused" channel would not produce runaway paper. Channels other
than 1 would be used for custom forms, where it would save time to skip across
part of the form rather than advancing line by line to the desired spot.
If you only ever used regular size paper this stuff wouldn't be obvious, but an
operator who had to handle other forms, like checks or label stock or anything
else that wasn't just plain 60/66 line pages, would have to change the paper
along with the matching format tape. Some printers had small local memories
that could be downloaded with the form definition tape data, avoiding the need
for the operator to switch the tape manually.
paul
